i liked your question and because of that i can tell you this
what i can say is (sorry about that but you asked for feedback i'm just telling everything in my mind that can make the game better)
the enemys was easy and i think you can make the game better by making the player poisoned and heal by killing the enemys
add amo to the gun so the player can not just hold left click and use range detection advantege
make the player faster
made enemys that can be killed with more then one shot
add dash to player and knife or katana levels
add some soud effects
fighting music
make the game feal more like retro by adding shaders
add some boss fights
you can make the UI more cooler "it is good but can be better"